Conn. Gen. Stat. § 12-121e

The assessor of any municipality that has adopted an ordinance pursuant to subparagraph (H)(xv) of subdivision (7) of subsection (c) of section 7-148 may reduce the assessment of any building that has been rehabilitated in accordance with the provisions of such ordinance. The assessment shall be adjusted after the building is rehabilitated. The adjusted assessment shall reflect the value of the structure prior to rehabilitation. The adjusted assessment shall be applicable for a period determined in accordance with the provisions of the ordinance.